Just to clarify — the reason my boot scripts sometimes spoof PowerMac1,1 isn't anything to do with the OS itself, but the Forth/OF boot script that runs before BootX to decide whether your machine is compatible with the OS or not. It's not a hard check for anything, it just checks the model number. You can patch the ISO if you prefer, but spoofing is easy. Oldworld g3beige is significantly different from an actual New World Yosemite-class PowerMac1,1.

Normally,interrupt controller should be in /pci/mac-io.For mac99 it exists there and has some properties.But in g3beige dev tree it is missing.Which is not normal.

If the boot-script wants PowerMac1,1, doesn't it mean that the OS is targetting BW,not G3B?And still it boots.It means that BW and G3B are compatible.

Is it that different?If you use the same spoofing with mac99 will you boot DP1 or Rhapsody?No.
It shows that BW and mac99 are really significantly different.
If the boot-script wants PowerMac1,1, doesn't it mean that the OS is targetting BW,not G3B?And still it boots.It means that BW and G3B are compatible.
I read that G3B is 1 of 2 Old World machines capable of booting MOSX(offically up to 10.2,with processor upgraded to G4 up to 10.5,just like BW).It makes it very similar to New World machines besides the boot method.

As an aside, I decided to try to get this up and running on my Raspberry Pi. Interesting results occurred.





This is using QEMU 2.8 master branch compiled from source, running Mac OS 9.2.2 with 256MB of RAM. As you can see, the colours are all black & white and rather distorted. Switching this to greys in Monitors panel improves a few things but the greys are actually inverted! I'm using 8-bit depth for the monitor, as using 16-bit causes the system to never make it past OpenFirmware, hanging just after the NVram offset warning message.

The system overall is very slow, menus visibly build themselves, the mouse doesn't track correctly and I haven't got sound up and running yet. But it works! There are also a couple of errors in the terminal regarding NVram starting position and I/O running over 1000 cycles too.

Command line used:



The Mac OS was installed on my main PC with QEMU 2.7, and simply moving the hard drive image over once installed worked wonders.

Edit: I switched the bit depth to 32 and we have colour!

I have both a Gossamer and Yosemite; the Gossamer is a SCSI-based legacy I/O machine, Yosemite is New World/ATA/USB, etc (it's been a loong time, but I /think/ the lowest end G4 (PCI) was on a modified Yosemite config). No variant of Gossamer booted Mac OS 8.6 from OpenFirmware, nor any variant of Sawtooth/mac99, so it's perhaps unsurprising that it doesn't quite like the device tree as-is.

Benchmarks, or it didn't happen

Why does sungem even exist now?

The only snag is that the sungem code is not yet in the qemu master code and therefore the "unofficial" build/patch is required.

Defining an 'FKEY' Resource to Invoke MacsBug 2
Another way to invoke MacsBug is to define an 'FKEY' resource using ResEdit or MPWS().Once you have defined this resource, you can use a Shift-Command-key combination to invoke MacsBug.
To define an 'FKEY' resource using ResEdit 2.1, follow these steps:
1. Launch ResEdit.
2. Open the 'FKEY' resource in the System File.
3. Choose “Create New Resource” from the Resource menu to create a new 'FKEY' resource.
4. Type the following numbers into the new resource exactly as shown:
A9FF 4E75
A9FF is machine code for the _Debugger trap; 4E75 is machine code for the RTS instruction.
Figure 2-6 shows what the resource looks like after you’ve entered the instruction.
Figure 2-6 Defining an 'FKEY' resource to invoke MacsBug
5. Choose Get Resource Info from the Resource menu and set its ID number to a number greater than 4 and less than or equal to 9. Please remember to use a number that is not already in use. The numbers 1, 2, 3, and 4 are reserved for system functions.
6. Close and save the System file.
7. To invoke MacsBug, press Command-Shift and the ID number you have assigned the resource. For example, if you’ve assigned the resource ID 7, press Command-Shift-7 to invoke MacsBug.
This method of invoking MacsBug will only work when the application is calling GetNextEvent or WaitNextEvent regularly, which it might not do if it’s hung or frozen.